1. Field of the Invention
This invention relates to the use of photovoltaics for waste heat recovery, and more particularly, to a device having photovoltaic cells, the device is mounted within and/or without the heating chamber of a furnace, e.g. a glass melting furnace, to convert waste heat in the form of visible red light and infrared light to electric energy
2. Discussion of Presently Available Technology
It is known in the art of industrial processing that a significant amount of the energy generated by furnaces used in industrial processes, e.g. but not limiting to the discussion, furnaces for melting glass batch materials is lost in the furnace waste or exhaust gases, or lost in the wasted radiated heat. Techniques for recovering heat from the exhaust gases and using the heat to generate electricity and/or to power mechanical equipment are discussed in U.S. patent application Ser. No. 11/958,574 filed Dec. 18, 2007 in the name of Adam D. Polcyn and titled HEAT PIPES AND USE OF HEAT PIPES IN FURNACE EXHAUST; U.S. patent application Ser. No. 11/958,565 filed Dec. 18, 2007 in the name of Adam D. Polcyn and titled A DEVICE FOR USE IN A FURNACE EXHAUST STREAM FOR THERMOELECTRIC GENERATION; U.S. Pat. No. 6,538,193 B1 and report titled DEVELOPMENT OF FRONT SURFACE, SPECTRAL CONTROL FILTERS WITH GREATER TEMPERATURE STABILITY FOR THERMOPHOTOVOLTAIC ENERGY CONVERSION authored by T. D. Rahmlow, Jr., D. M. DePoy, P. M. Fourspring, H. Ehsani, J. E. Lazo-Wasem and E. J. Gratiix.
Although the devices and methods disclosed in the above documents are acceptable for recovering waste heat from the exhaust gases of a furnace, there are limitations. More particularly, the exhaust gases of the furnace carry particles, e.g. particles of the materials being melted, that deposit on the surface of the heat recovery device and form a thermal insulating layer thereby reducing the heat recovery efficiency of the device. Periodically the insulating layer has to be removed from the outer surface of the device, e.g. by removing the device from the furnace as disclosed in U.S. Pat. No. 6,538,193 and/or removing the insulating layer while the device is in situ as disclosed in the above mentioned U.S. patent application Ser. Nos. 11/958,574 and 11/958,565. Further, another limitation of the devices used to recover heat from the waste or exhaust gases is that they are limited to recover waste heat from the exhaust gases and recover little if any of the waste heat radiated into the heating chamber of the furnace.
As can be appreciated by those skilled in the art, it would be advantageous to provide a technique and/or device that recovers waste heat radiated into the heating chamber of the furnace; converts the recovered radiated heat or energy to another useable form of energy; does not have the limitations of the devices that recover waste heat from the exhaust gases, and can be used with or without the devices that recover waste heat from the exhaust gases.